Preset transducer assembly



Jan. 12, 1960 c, NEUENDQRFFER EI'AL 2,921,285

PRESET TRANSDUCER ASSEMBLY Filed Jan. 19, 1959 Wis l2 9 53 44 J INVENTORS 45 OARL NEUENDORFFE'R 9 7 RAYMOND E. OLAFFL/ALJR.

5 ATTORNEY United States Patent PRESET TRANSDUCER ASSEMBLY Carl Neuendorlfer, Qoehitua'te, and Raymond E. Clafliin, Jr., Bedford, Mass, assignors to The Oiigear Company, Milwaukee, Wis, a corporation of Wisconsin Application January 19, 1959, Serial No. 787,595

9 Claims. (Ci. 338317) v .control panels of different thickness; and further objects of the invention are that the assembly provides accurate indexing in assembly and easily adjustable and positive presetting of limit positions of the transducer, that provides an oil and dust tight mounting on the control panel,

and that is easily disassembled without breaking or disconnecting the lead wires to the transducer. It is a further object that positive stops are selectively positionable in any radial position to limit the swing of the rotary transducer to preset limit positions but also that such stops may be employed to positively lock the rotatable element in any position.

Other objects and advantages of the invention will be apparent upon a reading of the following description with the accompanying drawings, in which:

Fig. l is a longitudinal cross sectional view of a potentiometer assembly mounted on a control panel and embodying the present invention;

Fig. 2 is a front view in elevation assembly shown in Fig. l;

Fig. 3 is a rear view in elevation assembly shown in Fig. 1;

Fig. 4 is a front view of a portion of the control panel of Fig. 1 showing the mounting hole for the potentiometer; and

Fig. 5 is ,a longitudinal cross sectional view of a front of panel portion of another potentiometer assembly embodying the present invention.

Referring to the drawings, an electromechanical signal transducer is shown, Fig. l, assembled and mounted on a control panel. The transducer assembly comprises one or more rotary type potentiometers 6, 7 ganged to a shaft 19 that extends through the control panel 8 in oil and dust tight relation therewith as hereinafter described.

The potentiometer assembly comprises subassemblies herein designated as a bracket assembly, a face plate assembly, a bushing assembly, and a knob assembly. The bracket assembly is disposed on the rear side of the control panel 8 and is secured thereto by suitable cooperating connections with a face plate 9 and a bushing 34 disposed on the front side of the panel. Front and rear designations for portions and surfaces of elements correspond in a directional sense to their assembled positions relative to front and rear of the control panel.

The bracket assembly comprises a U-shaped bracket 11 having a front leg 12 and rear leg 16. The front leg 12 has a potentiometer mounting hole therein, and a dished spring washer 23 or plate secured about its outer edges to the front face of leg 12. The bore of the spring washer 23 is coaxial of the mounting hole in the leg 12, and the central portion of the washer is spaced from the face of the leg. The annular inner portion of the washer defines a pilot flange 24 for alignment andseating in the hole 26 of the potentiometer of the potentiometer tween the annular flange Aligned pin receiving holes 27, 28 in the spring washer 23 and the leg 12 are centered at a radius corresponding to that of the bore or hole 26 in the control panel, which has a notch 29 therein through which a pin 31 or stud on the face plate 9 extends to lock the bracket 11 and face plate 9 and panel 8 together against rotation.

The bracket assembly further comprises ganged potentiometers 6, 7 having a threaded hub or sleeve 18 through which shaft it) rotatably extends. The potentiometers are mounted on the back of leg 12 with the sleeve 18 extending through the mounting hole and secured therein by a hex nut 21 screwed on the sleeve to clamp the potentiometer to the leg 12. The electrical resistance element and slide contact therefor, not shown, have external lug connections 2%, representing input and output connections and these are permanently connected by lead wires 17 to the studs 15 of corresponding screw type terminals 22 mounted and terminal mounting strips 13, 14 which are secured across an opening in the rear leg 16 of the bracket 11. 7

Control panels on which the illustrated preset unit may be mounted may vary in thicknesses, and the particul.-.r preset unit illustrated will accommodate a range of p nel thicknesses of 0.062 inch to 0.250 inch.

in the control panel.

lie-face plate assembly comprises a face plate 9 adapted to be seated on the face of the panel 8 with a bore 33 in the face plate coaxially aligned with the sleeve 18 and the bore in the panel. Pin 31 extends from the rear face of the face plate and into the notch 29 in the panel bore and into the holes 27, 28 in the bracket assembly for securing these members against relative rotation. A resil ient G-ring 32 is disposed in an annular groove in the rear face of the face plate for dust tight and oil tight engagement with the face of the panel. A dial plate 39 as shown, may be detachably secured to the outer periphery of the front face of the face plate 9 and suitably calibrated to represent positions or output voltages of the potentiometer.

The face plate 9 has a counterbore 36 defining an outer flange on which the dial plate 3th is mounted. The bushing assembly is substantially disposed within the counterbore 36 of the face plate.

The bushing assembly comprises a bushing 34 having a stepped outer configuration providing a series of annular steps 35, 39, 4t? stepped up from the rear of the bushing, and defining radial shoulders. A resilient O-ring 41 is disposed on a rear step 33 seating in a recess in the bottom of the counterbore when annular step 38 is disposed in the bore of the face plate. The rear end of the bore in the bushing 34 is threaded for engagement with the sleeve 18, each of which extend axially an amount sufficient, when assembled, to accommodate the range of thicknesses or widths of the control panels. The forward end of the bore in the bushing has a resilient O-riug 42 disposed in an annular recess therein for dust tight and oil tight engagement with the shaft 14).

A pair of stop supporting rings 47, 48 are disposed for rotation on the steps 39, 4t of the bushing. The rings have internal diameters corresponding to their steps and have substantially the same outer diameters as the diameter of the larger step or flange defining a front face 37 of the bushing. The width of the rings is less than that of the steps on which they are disposed so that they may be loose thereon. Studs 51 are rigidly secured to the outer periphery of the rings and extend axially beof the face plate and the bushing and forward of the front faces thereof. Stops '44, 4e are tensionally secured in threaded engagement with the studs 51, and each stop overlies the annular space between the face plate and the bushing and abuts the front faces thereof. A flat washer 52 and a spring washer r 3 53 are disposed under each stop to secure the stops against accidental loosening on their studs, for when tightened the stops and associated rings are clamped to the bushing. When the stops are loosened on their studs they may be selectively positioned in angular or rotative position about the bushing 34. The bushing assembly is disposed on the shaft and threaded to the sleeve 18 of the bracket assembly and'screwed tight to clamp the face plate 9 against the panel and secure the potentiometer assembly on the panel.

The knob assembly comprises a knob 56 having a knurled cylindrical surface and a radial arm or pointer 57 integral therewith. A split bushing 58 or sleeve insert is axially secured in a bore extending through the knob and set screws 59 in the knob 56 are arranged to press against the split bushing. A button 62 closes the l. An electromechanical signal transducer assembly including a rotatable shaft, stationary members through which said shaft extends adapted for flush mounting to a panel, said stationary members having radially allgned front faces with an annular space therein coaxial of front end of the knob bore and is secured by spring fingers pressed into bore. The knob assembly is mounted on the shaft 10in abutment with the bushing 34 and the set screws 59 are tightened, when the shaft and pointer positions are properly'indexe'd, so that the split bushing T holds, the shaft as a collet without marring the shaft and interfering with the accuracy of subsequent settings. The length of the shaft 10 and the length of the knob 56 are such that the free end of the shaft terminates.

within the knob when the potentiometer assembly is mounted ona thin or on a thick control panel within the predetermined range of thicknesses. I

For accurately indexing the knob pointer 57 relative to the shaft 10 the free end of the shaft is adapted to receive a tool inserted, into the bore in the knob and the free end is therefore provided with a slot 61 for receiving a screw driver. The knob is loosely mounted on the shaft 10' and secured against rotation by meansof the stops 44, 46 which positively lock the knob pointer in a predetermined index position, then by means of a screw driver the shaft 10 is rotated, until the potentiomter voltage or resistance corresponds to the knob pointer position, and then the set screws are tightened to secure the knob to the shaft. 7

In the potentiometer assembly described, the knob pointer. extends radially beyond the stops so that upon rotation of the knob and shaft therewith the swing of the pointer is limited to the selected preset positions of the stops, which may be preset in any selected positions and may be utilized to positively lock the pointer arm and the potentiometers output at any predetermined setting. r

The potentiometer assembly is thus constructed and arranged with subassemblies mounted coaxially of one another with the bushing assembly centering the'face plate concentrically of the potentiometer shaft thus pro viding a single reference axis for the various subassemblies to reduce the accumulation of tolerances which interfere with accurate indexing. Very accurate register between the position of the knob pointer and the elec= trical output is therefore possible and is secured, as above described, by rotation of the shaft within the knob with the pointer position fixed until the electrical output corresponds to the pointer position and then securing the knob for rotation with the shaft. i

Fig. 5 shows a preset unit assembly having a modified arrangement from that shown in Fig. 1 for the support said shaft, annular steps formed in one of said stationary membersjand withinsaid annular space, a pair-of rings disposed in said-annular space and each confined therein by a difierent one of said steps, a first stud secured to one of said rings and extending axially through said annular space, a first stop tensionally secured by said. first stud against the face of said one of the stationary members, a secondstud secured to the other of said rings and extending axially through said annular space,

a-second stop tensionally secured by said second stud againstthe face of said one of said stationary members,

and means'positioning said stops in selected radial posi-.

tions-so as to limit the rotation of said shaft between said selected positions. i

'2. In an assembly for an electromechanical transducer, a panel on'which said assembly is flush mounted, a stationary sleeve extending through said panel and a rotatable shaft extending through said sleeve, a bracket secured to said sleeve and abutting the rear face of saidpanel, a plate disposed coaxially of said sleeve in abutment with the front face of said panel, a bushing disposed coaxially of said shaft and secured to said sleeve in axially abutting relation to said plate for clamping said panel between said bracket and said plate, said plate and said bushing having radially spaced flange portions defining an open annular space having annular stepped surfaces, rings disposed on said stepped surfaces for rotation thereon and of stop supporting rings 63, 64. A face plate 66 has a bushing receiving counterbore with a bushing 67 disposed therein in threaded engagement with a sleeve 18 of the potentiometer. One stop supporting ring 64 is disposed on an annular step of the bushing 67 with a stud 69 secured to its radially outer periphery. The other stop supporting ring 63 is a split ring disposed concentrically of the first within an annular groove formed in the wall of the counterbore in the face plate. A stud 68 is secured to the radially inner periphery of ring 63 and studs for both rings 63, 64 maybe as shown at the same radial distancev from the axis of the shaft and axially spaced and confined .by said stepped surfaces Within said annular space, first and second stops overlying said annular space, axially extending means adjustably connecting said stops to: different said rings so that said stops may be rotated to any selected radial positions and secured in frictional engagement with the faces of said bushing and said plate, and a pointer mounted for rotation with said shaft and extending radially for engagement with said stops to limit the rotation of said shaft to angular positions between said stops.

'3. 'A potentiometer assembly including a panel through which a potentiometer extends in fluid tight relation, said potentiometer having'a frame including a stationary sleeve extending through said panel, a'rotatable shaft for ad justment of said potentiometerextending through said sleeve, a'bracket secured to said frame, and abutting a rear face of'said panel, a ring plate disposed coaxially of said sleeve in axial abutment with a front face of said panel, a first O-ring seal disposed in an annular groove in the abutting faces of said panel and said ring plate, a bushing having a front portion in sealing engagement with said shaft anda rear portion in threaded engagement with said sleeve and in axially abutting relationship to said ring plate, a second O-ring seal disposed between said abutting face of said ring plate and bushing, said bushing having annular steps formed in its outer periphery with the step diameters increasing toward the front end thereof, a pair of rings of internal diameters corresponding to said steps disposed'for rotation on adjacent steps and having axial thicknesses shorter than the axial length of their corresponding steps, a first stop and connecting means clamping shoulder of a step between one'of 's'aid tion of said rings and said first stop, and a second stop and connecting means clamping a shoulder of another step between the other of said rings and said second stop, and a pointer arm mounted for rotation with said shaft and extending radially between said stops.

4. A potentiometer assembly comprising a stationary frame, a sleeve rigid with said frame, a shaft rotatable in said sleeve for varying the operating characteristics of the potentiometer, a panel on which the assembly is adapted to be mounted and including a bore through which said sleeve extends with said frame abutting a rear face of said panel, a bushing disposed on said shaft and said sleeve with a front end of said bushing providing a sealing engagement with said shaft and a rear end of said bushing being in threaded engagement with said sleeve, said bushing having an outer surface of stepped configuration providing a series of annular steps and shoulders, a ring plate disposed about a rear step of said bushing and urged by a shoulder thereof against the front face of said panel, sealing means provided between abutting faces of said ring plate and panel and between abutting faces of said ring plate and said bushing, a first ring loosely fitted on a second said step and axially confined thereon by a shoulder thereof and said ring plate, a second ring loosely fitted on said third step and axially confined thereon by a shoulder thereof and said first ring, said ring plate having an annular flange extending axially and radially over said rings, a pair of stops abutting a front face of said flange of said ring plate and a front face of said bushing, stud means extending axially from each said ring and adjustably connected to said stops so that said stops may be circumferentially positioned and secured in any selected positions, and a pointer arm mounted on said shaft for rotation therewith, said pointer arm extending radially between said stops for limiting the rotashaft to the angular positions defined by said stops.

of said bracket and having a stationary sleeve and a rotatable shaft therein extending forward through said front leg, a terminal strip mounted on the rear leg of said bracket with the terminals thereof connected to terminals of the transducer, and a dished washer secured on the frontface of said front leg coaxially of said sleeve and said bushing and having a pin receiving hole therein adapted to align with the pin receiving notch in the bore of the panel and the dished washer adapted to seat on said bore with the sleeve and shaft extending therethrough to the front of the panel; said face plate subassembly comprising a face plate having a central bore and a counterbore in the front face thereof which defi: es an annular flange, an annular groove and a resilient O-ring disposed in the rear face of said face plate, and a pin rigid with said face plate and extending axially from the rear face thereof and adapted to extend through said notch in the bore of the panel and into the hole in the dished washer of the bracket assembly to radially align and non rotatably secure the bracket and face plate relative to the panel; said bushing assembly comprising a 5. An electromechanical signal transducer assembly I including a stationary element and a rotatable element, a bracket supporting said stationary element on a rear face thereof, a sleeve secured to said bracket and extending axially of its front face, a shaft connected to said rotatable element and extending through said bracket and said sleeve, a panel having an aperture through which said sleeve and said shaft extend with the front of said bracket in abutment with a rear face of said panel, a bushing coaxially mounted on said sleeve in threaded engagement therewith, sealing means disposed in the front end of said bushing to provide an axial oil tight seal between said bushing and said shaft, said bushing having an annular outer surface configuration defining a series of steps and shoulders, a face plate having a bore and a counterbore therein with a rearward first said step of said bushing fitted in said bore and with second and third said steps disposed in said counterbore, a resilient 0-ring disposed on the first step of said bushing for sealing engagement with said face plate, another resilient O-ring disposed in an annular groove in the rear face of said face plate in sealing engagement with the front face of said panel, a pair of rings disposed for rotation on the second and third steps of said bushing, a stud secured to the radially outer portion of each of said rings and projecting axially forward in said counterbore, and a stop secured to each said stud and having a surface overlying a portion of the front faces of said face plate and of said bushing and ur ing said rings in clarnping engagement with their associated said shoulders.

6. An electromechanical transducer assembly adapted for relatively flush mounting on a control panel provided with a bore and an axially extending pin receiving notch in said bore for receiving the transducer assembly comprising a bracket subassembly, a face plate subassembly, a bushing subassembly, and a knob subassembly; said bracket subassembly including a U-shaped bracket, an electromechanical transducer mounted on a front leg bushing for mounting on said shaft and having a steppedup outer configuration from a rear end thereof to define a series of steps and shoulders, a resilient O-ring disposed on a rear said step that extends through said bore in said face plate, a pair of stop supporting rings disposed for rotation on the next pair of said steps, stubs extending forward from the outer periphery of said rings, stops abutting a front face of said bushing and in threaded engagement with said studs so that when tightened thereon said stops are secured in selected positions radially of said bushing, a resilient O-ring disposed in an annular groove within the bore of the bushing at the front end thereof and adapted to provide a sealing engagement with the shaft, and the rear end of the bore of the bushing being threaded to an axial length suflicient for threaded engagement with said sleeve to accommodate control panels of a predetermined range of thicknesses; and said knob subassembly mounted on said shaft against said bushing and comprising a knob having means detachably clamping said knob to said shaft, and a pointer arm extending radially of said knob for circumferential engagement with said stops upon rotation of said shaft with said knob.

7. An electromechanical transducer assembly adapted for relatively flush mounting on a control panel provided, with a bore for receiving the transducer assembly comprising a bracket subassembly, a face plate subassembly, a bushing subassembly, and a knob subassembly; said bracket subassembly including a U-shaped bracket, an electromechanical transducer mounted on a front leg of said bracket and having a stationary sleeve and a rotatable shaft therein extending forward through said front leg, a terminal strip mounted on the rear leg of said bracket with the terminals thereof connected to terminals of the transducer, and a dished washer secured on the front face of said front leg coaxially of said sleeve said bushing and adapted to seat on said bore with the sleeve and shaft extending therethrough to the front of the panel; said face plate subassembly comprising a face plate having a central bore and a counterbore in the front face thereof which defines an annular flange; said bushing assembly comprising a bushing for mounting on said shaft and having a stepped-up outer configuration from a rear end thereof to define a series of steps and shoulders, a rear said step extending through said bore in said face plate, a pair of stop supporting rings disposed for rotation on other of said steps, stubs extending forward from the outer periphery of said rings, stops abutting a front face of said bushing and in threaded engagement with said studs so that when tightened thereon said stops are secured in selected positions radially of said bushing, and the rear end of the bore of the bushing being threaded to an axial length sufiicient for threaded engagement with said sleeve to accommodate ;control panels of a predetermined range of thicknessesrand said knob subassembly adapted for mounting on said shaft against said bushing and comprising a knob having a shaft receiving bore therethrough, a split sleeve bushing axially secured in said bore for receiving said shaft a set screw in said knob adjnstably bearing against said sleeve for detachably clamping said sleeve to said shaft, and a pointer extending radially of said knob for circumferential engagement with said stops upon rotation of said shaft with said knob, said knob having an axial length to accommodate said predetermined range of thicknesses for the control panel so that the shaft end is disposed within said knob, and a button closure for the-front end of the knob bore removable therefrom to provide access to the end of the shaft for adjustment of the rotative positionof the shaft relative to the pointer. I r

8. An electromechanical transducer assembly adapted for relatively flush mounting on va control panel provided with a bore and an axially extending pin receiving notch in said bore for receiving the transducer assembly com prising a bracket subassembly, a face plate subassembly, a'bushing subassembly, and a knob subassembly; said bracket subassembly, an electromechanical transducer mounted on said bracket andhaving a stationary sleeve and a rotatable shaft therein extending forward there through, and a dished washer secured on the front face of said bracket coaxially of said sleeve and having a pin receiving hole therein adapted to align with the pin receiving notch in the bore of the panel and the dished washer ment with said studs so that when tightened thereon said i stops are secured in selected positions radially of said bushing, and thetrear end of the bore of the bushing being threaded to an axial length sufficient for threaded engagement with said sleeve to accommodate control panels of a predetermined range of thicknesses; and said knob subassembly adapted for mounting on said shaft against said bushing and comprising a knob having a shaft receivingr bore therethrough, a split sleeve bushing axially secured in said bore for receiving said shaft, a set screw in said knob adjustably bearing against said sleeve for detachably clamping said sleeve to said shaft, and a pointer extending radially of said knob for circumferential engagement with said stops upon rotation of said shaft with said adapted to seat on said bore with the sleeve and shaft extending therethrough to the front of the panel; said face plate subassembly comprising a face plate having a central boreand a counterbore in the'front face thereof which defines an annular flange, a calibrated dial face detachably secured to the face of said flange and a pin rigid with said face plateand extending axially from the rear face thereof and adapted to extend through said notch in the bore of the paneland into the hole in the dished washer of the bracket assembly to radially align andnonrotatably secure the bracket and face plate relativev to the panel; said bushing assembly comprising a bushing for mounting on said shaft and having a stepped-up outer configuration from a rear end thereof to define a series of steps and shoulders with a rear said step adapted to extend through said bore in said face plate for centering said face plate concenof the shaft relative'to the pointer.

knob, said knob having an axial length to accommodate said predetermined range of thicknesses for the control panel so that the shaft end remains disposed within said knob, and a button closure for the front end of the knob bore removable therefrom to provide access to the end of the shaft for index adjustment of the rotative position 9. An electromechanical signal transducer assembly including a rotatable shaft, stationary members through which said shaft extends adapted for flush mounting to a panel, said stationary members having concentric portions with aligned front faces and defining an annular space coaxial of said shaft, a pair of rings disposed between said members within said annular space, first stud securedto one of said rings and extending axially through said an- 7 I nular space, a'first stop tensionally secured by said first 'stud against one of said faces of said members, a second stud secured to the other or said rings and extending axially through said annular space, a second'stop tensionally securedby s'aidsecond stud against one of said faces of said members, and means positioning said stops in selected radial positions so as to limit the rotation of said shaft between said selected positions and to positively secure said shaft in a given one of said positions.

References (Cited in the file of this patent UNITED STATES PATENTS 882,569, 7 Knight a Mar. 24,1908 

